Rontgen apparatus



Nov. 24, 1931. J. HOFMANN 1,333,073

RC'JNTGEN APPARATUS Filed Oct. 6. 1927 Patented Nov. 24, 1931 UNITE!) STATES,

PATENTS orrice JOSEE HOFLEAI-l'lfl', BERLIN, GERL'IANY, ASSIGNOR TO THE FIRMI: ELEKTRIZITATSw} GESELZSCI-IAFT SANITAS M. B. H., OF BERLIN, GERMANY nonrenn APPARAT S Application filed October 6, 1927, Serial No; 224,4=70, and in Germany October 9, 1926;

My invention relates to improvements in Rontgen apparatus, and the object of the im-' provements is to provide, in connection with a Rontgenapparatus, automatic means for interrupting the current in case the intensity of the current flowing through the Rontgen tube isincreased beyond a certain maximum,

which may be the case for example in case of Y short circuit, a break-down of the resistance of the tube, etc'. The said safety device is arranged so to act on the primary or lowvoltage current of the system, and itmust be controlled by the liiglrvoltage current flowing through the Rontgen tube. Therefore, I provide means intermediate the high voltage side and the low-voltage side of the safety device for preventing the transmission of the highpotential to the low-voltage side. For this purpose the safety device is not directly includedin the high-voltage circuit, but in a subsidiary circuit coupled with the high-voltage circuit by means of a trans former, the primary and secondary of the said transformer being separated from each other 7 by an insulation preventing the transmission of the high voltage.

For the purpose of explaining the invention several examples embodying the same have been shown in the accompanying drawing, showing in Figs. 1 to 6, several examples embodying the invention in a diagrammatical way.

Referring now to the example illustrated in Fig. 1, the primary 5 of a high-voltage 5 transformed T is included in the net a, and

the secondary 0 of the said transformer is included in the highvoltage circuit d of the Rontgen tube 0. Further, the primary circuit a includes a switch arm f forming a 40 part of an electromagnetic switch apparatus 7 responsive to current intensity. The electromagnetic coil 7' of the said safety switch is incluoed'in a subsidiary circuit 2'. The switch arm 7 is acted upon by a spring f and it is adapted to be locked by means of a nose f of a spring-pressed pawl f an arm f of the said pawl projecting through the wall of the casing for operation of the pawl by hand. The circuit 2' is energized by the secondary Z of a transformer T the primary is of which is included in the high-voltage circuit d of the Rontgen tubeclose to the high-voltage terminal of the transformer T. The coils and Z are separated: from each Y other by an insulation m adapted to prevent" the transmisslon' of high Voltage. The transformer T transforms the high-voltage current of the circuit oil into low potential current, so that-the safetyswitch f receives only low voltage. The switchf is regulated so that normally the current intensity within the circuit 71 is not sufficient for operating the same. If however'the intensity of the current flowing throughthe circuit d increases beyond a certain maximum, for example by a shortcircuit, the switch arm f of the safety switch f is attracted by the coil f thus interrupting the primary circuit a. Such a circuit may be produced for example by a person p making contact simultaneously with both terminalsof the transformer T, as has been indicated in the figurein dotted lines. Now the springpressed pawl f locks the switch arm f in position for interrupting the circuit until it is returnedinto releasing position by a pressure on the arm f whereupon the switch arm is returned into circuit closing position by the spring f. i

Any known or preferred safety switch f may be provided in the system. It is an portant that the transformer T be disposed as close as possible to the high-voltage ter minal of the high-voltage transformer, so that the safety'system may be operated by any part ofthe circuit. In Fig. 2, which is' therwise similar to Fig.1, the transformer T 'ha-s been included in the box 9 enclosing the transformer T.

In the systems so far described the safety switch f may fail to o crate in case of a short circuit of the trans ormer T Therefore, Fig. 3 shows a -modification in whichthe secondary c of the transformer T is divided into two sections, and the transformer T is located between the said sections.

through the secondary c.-

When providing a transformer T at one In this -modification the safety system will be operside of the transformer T, the system may fail to act for example by a connection to the ground. Therefore, Fig. l shows a modification in which two transformers T and T the latter having its primary included in the high voltage circuit and its secondary included in the supply current are provided one at each side of the transformer T, the said transformers T and T being preferably connected in series with a single safety switch 7". If a person 72 touches the high-voltage circuit (Z for example at the point 1, the potential of the adjacent terminal of the secondary c is reduced to zero, while the potential of the other terminal is doubled. If now by reason of the said increase of the potential a short-circuit current flows for example from h over 0 tothe ground, the transformer T is short-circuited so that it is ineffective. But the said short-circuit cur rent flows from ground over p, n, c, is, h, 0 to ground, so that the transformer T operates the safety switch f.

In Fig. 5 I have shown a modification in which the primary circuit of the Rontgen apparatus is switched out at any desired current intensity of the Riintgen tube. As shown a regulatable resistance Q is connected in shunt to the safety switch f, one terminal of the said resistance being connected by a lead 7' to one terminal of the coil Z and the movable contact '9 of the said resistance is connected to the other terminal of the coil Z. The current generated in the transformer T is divided according to the regulation of the resistance 9 at different ratios, one part flowing through the said resistance, and the other through the safety switch f, so that the said safety switch can be operated by currents of different intensitiesflowing through the high-voltage circuit.

Further, in this modification the current of the net passes through an auto-transformer s and an ohmic resistance a into the primary Z) of the high-voltage transformer, the said auto-transformer lmving the function to regulate the voltage and being adapted to be regulated by means of a contact lever 75, and the ohmic resistance u being adapted to be regulated by means of a movable contact o. The object of the ohmic resistance a is to bridge the steps of the voltage of the autotransformer, and it is switched in when using the Rtintgen system for radioscopic purposes, while it must be switched out when making photographs, because it would be broken by the high current intensity needed for taking photographs. On the other hand, when taking photographs requiring current intensities of from 20 to 100 millian'ipere the safety switch f must be regulated so as to be less sensitive. By connecting the movable contacts 1' and 1) through the member w the said regulating operations are made dependent on each other.

Finally, as has been illustrated in Fig. 6, the safety switch can be used for limiting the load of the Rontgen tube. Each Rontgen tube is capable of a certain load written on a shield fixed to it. If it is desired automatically to prevent breaking of the Rontgen tube by the safety switch, the said safety switch must be constructed so that the intensity of the current is smaller in case of high voltage of the tube, than in case of low voltage. For this reason the movable contact 1 of the resistance 9 is positively connected with the contact lever r of the voltage switch 8, for which purpose it is connected by an insulating arm 3 with the lever 25 or the fulcrum thereof, and for making the movable connection with the lead 7", the said movable contact adapted to slide on a contact segmentconnected with the said lead j.

I claim:

A Rontgen system, comprising a primary circuit including a voltage controlling switch, a secondary circuit including the Rontgen tube, a high-volta e transformer having its primary included in said primary circuit and its secondary in said secondary circuit, a safety apparatus for the control of said primary circuit and having a coil, a third circuit including said coil, a second transformer having its secondary included in said third circuit and its primary included in said secondary circuit, and a variable resistance connected in shunt to said coil, and having a regulating member being dependent upon said voltage controlling switch.

In testimony whereof I afiix my si nature.

J OSEF HOFMANN. 

